Blending of irregularly shaped particles

Existing blending theories have mostly been verified in the past by mixing of monosized, smooth, spherical particles. In this study, binary mixing of non-spherical particles with rough surfaces is shown to adhere to diffusional mixing equations as long as the mean diameters of the two fractions (A and B) are identical, i.e.d_A = d_B. When this is not the case, blending rates (diffusional coefficients of blending, D) reduce drastically when the small particles are not of such a size that they will fit into the interstices between the larger particles. It is shown also that the final standard deviation in these cases is many orders of magnitude higher than the predicted random standard deviation. When d_A = d_B, the diffusion coefficient will depend on the magnitude of d_A. The diffusion coefficient is not a function of the ratio of A to B. In blending in a horizontal mixer, D decreases with addition of lubricant. This is not the case in a V-blender, where bulk mass transfer appears to be the controlling step. In all other respects, V-blending is identical, functionally, to the profiles obtained in cylindrical blending.